Editable node/link text Issue

on editing a node or link lable on mydiagram the old text get visible on background of node / link
is it possible to set the height of text-area dynamically on node edit or is there any event of node / link on edit it.

You can customize the text editor as much as you like: GoJS HTML Interaction -- Northwoods Software and GoJS HTML Interaction -- Northwoods Software.

The default text editor implementation is available at: https://gojs.net/latest/extensions/TextEditor.js. That default editor is demonstrated at: HTMLInfo Text Editor.

The default behavior is to automatically resize the textarea so that it fits around what the user has typed. That way there is always room for more text, visually.

In your example I assume the user has already replaced/deleted most of the text, which is why some of the edited TextBlock is visible behind the textarea.

I suppose there could be a minimum size that matches the original size of the TextBlock. You could set the min-width and min-height CSS properties in the TextEditor.show function in that TextEditor.js file.